Non-parasitic Seed Disorders of Major Agricultural Crops

Abstract

Non-parasitic seed disorders are the abnormalities in seeds caused by environmental and nutritional stresses, alterations in genetic makeup, or some mechanical injuries caused to the seeds during harvesting and handling of the crop. These disorders are not caused by any infectious agent, but they can make the seed susceptible to infection by many pathogens. This chapter describes the identification, cause, and management of seed disorders of field and vegetable crops. Disorders caused by environmental stresses like high or low temperature, humidity, moisture, frost, and drought are generally irreversible; however, their incidence can be minimized by opting suitable sowing and harvesting time along with providing adequate seed storage conditions. Disorders like yellow berry, hollow heart, and marsh spot, which are caused by the deficiency of different nutrients, can be avoided by providing a balanced nutrition to the seed crops by soil and foliar application of the deficient nutrients. Mechanical injuries during threshing and seed processing also result in many seed disorders. Baldhead or snakehead in beans, for example, is a common disorder that occurs due to injury at any stage including harvesting, threshing, cleaning, or during seed sowing operations. Disorders caused by genetic mutations can be reduced by breeding for stress-resistant cultivars of various crops by gene transfer and devising efficient screening protocols to screen genotypes against various abiotic stresses.